Ensure that GC#deleteOrphans respects pack lock
If pack or index files are guarded by a pack lock (.keep file) deleteOrphans() should not touch the respective files protected by the lock file. Otherwise it may interfere with PackInserter concurrently inserting a new pack file and its index. The problem was caused by the following race. All mentioned files are located in "objects/pack/". File endings relevant in "pack" dir: .pack .keep .idx .bitmap When ReceivePack receives a pack file it executes the following steps: ReceivePack.service(): receivePackAndCheckConnectivity(): receivePack(): receive the pack parse the pack, returns packLock (.keep file) PackInserter.flush(): write tmpPck file: "insert_<random>.pack" write tmpIdx file: "insert_<random>.idx" real pack name: "pack-<SHA1>.pack" real index name: "pack-<SHA1>.idx" atomic rename tmpPack to realPack atomic rename tmpIdx to tmpIdx execute commands unlock pack by removing .keep file trigger auto gc if enabled When PackInserter.flush() renames the temporary pack to the final "pack-xxx.pack" file the temporary pack index file "insert_xxx.idx" has no matching .pack file with the same base name for a short interval. If deleteOrphans() ran during that interval it deduced the pack index file was orphaned. Subsequently the missing pack index caused MissingObjectExceptions since objects contained in the pack couldn't be looked up anymore. Bug: https://bugs.chromium.org/p/gerrit/issues/detail?id=13544 Change-Id: I559c81e4b1d7c487f92a751bd78b987d32c98719 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
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@ -57,11 +57,15 @@ public class GcOrphanFilesTest extends GcTestCase {
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private final static String BITMAP_File_1 = PACK + "-1.bitmap";
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private final static String IDX_File_2 = PACK + "-2.idx";
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private static final String BITMAP_File_2 = PACK + "-2.bitmap";
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private static final String IDX_File_2 = PACK + "-2.idx";
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private final static String IDX_File_malformed = PACK + "-1234idx";
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private final static String PACK_File_2 = PACK + "-2.pack";
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private static final String KEEP_File_2 = PACK + "-2.keep";
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private static final String PACK_File_2 = PACK + "-2.pack";
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private final static String PACK_File_3 = PACK + "-3.pack";
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@ -105,6 +109,22 @@ public void malformedIdxNotDeleted() throws Exception {
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assertTrue(new File(packDir, IDX_File_malformed).exists());
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}
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@Test
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public void keepPreventsDeletionOfIndexFilesForMissingPackFile()
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throws Exception {
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createFileInPackFolder(BITMAP_File_1);
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createFileInPackFolder(IDX_File_2);
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createFileInPackFolder(BITMAP_File_2);
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createFileInPackFolder(KEEP_File_2);
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createFileInPackFolder(PACK_File_3);
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gc.gc();
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assertFalse(new File(packDir, BITMAP_File_1).exists());
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assertTrue(new File(packDir, BITMAP_File_2).exists());
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assertTrue(new File(packDir, IDX_File_2).exists());
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assertTrue(new File(packDir, KEEP_File_2).exists());
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assertTrue(new File(packDir, PACK_File_3).exists());
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}
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private void createFileInPackFolder(String fileName) throws IOException {
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if (!packDir.exists() || !packDir.isDirectory()) {
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assertTrue(packDir.mkdirs());
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@ -148,6 +148,8 @@ public class GC {
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private static final String INDEX_EXT = "." + PackExt.INDEX.getExtension(); //$NON-NLS-1$
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private static final String KEEP_EXT = "." + PackExt.KEEP.getExtension(); //$NON-NLS-1$
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private static final int DEFAULT_AUTOPACKLIMIT = 50;
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private static final int DEFAULT_AUTOLIMIT = 6700;
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@ -978,7 +980,10 @@ private void deleteOrphans() {
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fileNames = files.map(path -> path.getFileName().toString())
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.filter(name -> (name.endsWith(PACK_EXT)
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|| name.endsWith(BITMAP_EXT)
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|| name.endsWith(INDEX_EXT)))
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|| name.endsWith(INDEX_EXT)
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|| name.endsWith(KEEP_EXT)))
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// sort files with same base name in the order:
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// .pack, .keep, .index, .bitmap to avoid look ahead
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.sorted(Collections.reverseOrder())
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.collect(Collectors.toList());
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} catch (IOException e1) {
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@ -990,7 +995,7 @@ private void deleteOrphans() {
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String base = null;
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for (String n : fileNames) {
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if (n.endsWith(PACK_EXT)) {
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if (n.endsWith(PACK_EXT) || n.endsWith(KEEP_EXT)) {
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base = n.substring(0, n.lastIndexOf('.'));
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} else {
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if (base == null || !n.startsWith(base)) {
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